Process for treatment of flax



Patented Oct. 29, 1929 UNITED STATES PATENT OFFICE I OWEN DAVID LUCAS 'OF WESTMINSTER, LONDON, ENGLAND, .ASSIGNOR TO VIGKERS LIMITED, OF WESTMINSTER, ENGLAND, A COMPANY OF ENGLAND PROCESS FOR TREATMENT OF FLAX No Drawing. Application filed January 13, 1928, Serial No. 246,658, and in Great Britain July 5, 1927.

This invention relates to the treatment of flax, its object being to produce a fibre resembling silk. The flax fibre treated may be either separated from the straw by retting and scutching, or obtained directly by scutching the green straw.

In known processes cotton fabrics after a treatment with lye have been subjected to the action of a cellulose solvent of such strength as to exert a selective dissolving and hydrolyzing action on the fibre without dissolving or completely gelatinizing it, and cuprammonium and zinc chloride are known to be suitable as such solvents, but it is believedthat such processes have not hitherto been successfully applied to the treatment of flax and the present invention consists in the modified process which renders it technically feasible to apply the solvent treatment to flax. According to this invention the solvent treatment when applied to retted fibre is preceded by boiling the fibre in a 5% solution and washing with water, and the said solvent treatment is followed by thorough washing and boiling in a 1% solution of caustic soda to which is added a plasticizer, again washing, immersion in an acid bath, then a final washing and drying. In the case of unretted scutched fibre, the process as above specified is preceded by boiling for 1 hour in a 1% solution of caustic soda and washing with water. When zinc chloride solution is employed as the solvent, its concentration is and when other solvents are used their concentration should be such as to exert an equivalent action on the fibre.

The following examples may be given'of the application of the invention to the treatment of flax In the case of pre-retted fibre, it is first boiled for 1 hour in a 5 per cent solution of caustic soda, then washed with cold water.

In the case of unretted fibre it is considered desirable to begin by boiling it for 1 hour in a 1 per cent solution of caustic soda, then wash it. After this it is boiled for 1 hour in a 5 per cent solution of caustic soda, removed from this solution and washed in either hot or cold water until it ceases to dis- The fibre after undergoing either of the above mentioned preliminary processes is placed in the cellulose solvent, care being taken that the whole of the fibre is equally impregnated with the solvent as quickly as possible. This solvent may be cuprammonium containing 10 grammes of copper to the litre dissolved in ammonia solution of .880 specific gravity and diluted with an equal volume of water, the fibre being immersed in this solution for 5 to 10 minutes. Instead of cuprammonium a solution of zinc chloride containing 50 parts by weight of zinc chloride to 50 parts of water may be used. After squeezing out as much of the solvent solution as possible, the fibre is thoroughly washed in cold water and then boiled for 1 hour in a 1% solution of caustic soda to which at the end of the first half hour is added a plasticizer which maybe a sulphonated fatty acid such as sulphonated castor oil, or an alkyl-sulphonamide of a similar fatty acid, to which may be added A to its weight of linseed oil or other partly saponifiable oil, the proportions used for 10 0 lbs.

of retted fibre being approximately 100 gal ions of 1% caustic soda and 1 to 3 lbs.of the j plasticizer.

If the fibre has been treated with I cuprammonium, and then boiled in 1% caus- J tic soda with a plasticizer it is treated with a 50 per cent solution of sulphuric acid until the whole of the colour has been removed, j

or instead of sulphuric acid a 5 per cent solution of hydrochloric acid may be used,

The sulphuric acid has been found to give the better result after cuprammonium:

Where zinc chloride is used the fibre after changed, the plant structure being almost completely broken down, and the product consisting of almost colourless translucent rods. This product resembles artificial silk, having a high lustre and being soft and capable of being combed into fibres of extreme fineness. 1

After the aforesaid step of the process in which the fibre is boiled in the 5 per cent solution of caustic soda, the fibre may be'washed and completely dried, then placed for 12 hours in carbon bisulphide, again dried, and then subjected to another boiling in a 1 per cent solution of caustic soda and subjected to the remainder of the process already described, the interposition of this additional treatment giving a good silk-like fibre.

What I claim and desire to secure by Letters Patent of the United States is 1. A process of treating flax fibre, comprising the steps of retting, boiling in a 5% caustic soda solution, Washing with water, immersing in a cellulose solvent, again wash ing, boiling in a 1% caustic soda solution with a plasticizer, again washing, immersing in an acid bath, finally washing, and drying.

2.,A process of treating flax fibre, comprising the steps of boiling in a 1% solution of caustic soda, washing with-water, boiling in a 5% caustic soda solution, washing with water, immersing in a cellulose solvent, again wash1ng,b01l1ng 1n a1% caustic soda solution wlth a plastlcizer, again Washing, immersng 1n an acid bath, finally washing, and drymg.

3. A process of. treating flax fibre com- 7 v prising the steps of retting, boiling in a 5% caustic soda solution, Washing with water, dryin g, immerslng in carbon bisulphide, drying, boiling in a 1% caustic soda solutlon,

- again washing, immersing in a cellulose solvent, again washing, boiling in a 1% caustic soda solution with a plasticlzer, again washing, immersing 1n an acid bath, finally washing and drying,

4. A process of,treat1 ng flax fibre comprising the steps of boiling in a 1% solution of caustic soda, washing with water, boiling in a 5% caustic soda solution, Washing wit water, drying, immersing in carbon bisulphide, drying, boiling in a 1% caustic soda solution, again washing, immersing in a cellulose'solvent, again washin boiling in a 1% caustic soda solution wit again washing-immersing in an acid bath, finally washing, and dryin OWEN D VID LUCAS.

a plasticizer, v 

